Hi,
There is no camping in Francorchamps itself. And the parkings should be filled by then I fear

In the neighbourhood:
P= parking
C= camping
M= aire
W= wild
SPA (74C1)(= page Michelin Benelux)
● P Hôtel de Ville , centre
● P Parc des Sources, Rue de la Sauvenière
● C »Sources » 4pl MH
STAVELOT (72C2)
● P abbaye, 5pl N 50 23 40.1, E 5 55 59.4
MALMEDY (73D2)
● M ex station , 5€/24h, N 50 25 22.4, E 6 1 44.4
● C ”Camping Familial” Arimont
COO (72C3)
● P Cascade , wc, N 50 23 35.2 E 5 05 31.56
●>Electricité > P (isolated ) wc, N 50 23 14.6, E 5 52 27.1
HOCKAY (72C2)
● W > end Chn de la Hoëgne, N 50 29 17.2 E 5 59 35.8 (not suitabable for long MH: dead end !)
SART lez SPA (72C1)
● P > church
● >Sart Station : P Roquez (> Hoëgne) N 50 30 29.6, E 5 57 37.1
Farther away in the ‘Hautes Fagnes’ a lot of wilding places : Baraque Michel, Mont Rigi, Signal de Botrange …
Have also a look at:
http://www.wildcamping.co.uk/forums/belgium/3368-belgium-wallonie-province-de-liege.html
Don't speed

Leo